Light emitting diodes (LEDs) are semiconductor devices that use characteristics of compound semiconductors to convert electricity into ultraviolet rays, visible light, or infrared rays, which are widely used in home appliances, remote controls, and large scale electronic displays.
Especially, high luminance LED light sources are used in lighting devices, and have high energy efficiency and long service life to decrease replacement costs. Furthermore, such high luminance LED light sources are resistant to vibration or shock, and do not require poisonous substances such as mercury, and thus, replace typical incandescent lamps or fluorescent lamps in terms of energy conservation, protection of the environment, and cost saving.
In addition, LEDs are appropriate as light sources for medium to large liquid crystal display (LCD) TVs and monitors. Particularly, since LEDs are superior in color purity, power consumption, and miniaturization to cold cathode fluorescent lamps (CCFLs) that are widely used in LCDs, various products include LEDs, and active research is being carried out on LEDs.
Moreover, various technologies of using blue LEDs and quantum dots (QDs) as a phosphor for emitting red light and green light to emit white light are being introduced. White light emitted using such quantum dots has high brightness and excellent color reproductivity.
However, research is needed to decrease optical loss and color unevenness of LEDs used in a backlight unit.